Such a device has been known from U.S. Pat. No. 4,546,491. Such devices are used to enable pilots or astronauts to withstand higher positive accelerations during flight maneuvers without an excessive accumulation of blood in the legs and consequently an excessive undersupply of blood in the head occurring, which may cause the pilot to faint during high positive acceleration. The term positive acceleration always pertains in connection with the present invention to the pilot who wears the control device and for whom a positive acceleration causes an increased weight pressing him into the pilot seat.
Positive accelerations of up to about +9 g, i.e., nine times the gravitational acceleration, can be currently reached with good life support systems in jet aircraft. This is possible if the pilot wears so-called anti-g pilot pants, which contain inflatable chambers that surround the legs, can be pressurized and exert an increased pressure on the legs of the pilot when the pressure values in the chambers increase in order to thus counteract a dilation of the blood vessels and an intense accumulation of blood in the legs of the pilot at high positive accelerations. To make it possible to admit pressure into the anti-g pilot pants as needed, control devices such as that described in U.S. Pat. No. 4,546,491 have been known, which hae an inlet for compressed gas and a controller outlet, which is to be connected to the anti-g pilot pants and at which an outlet pressure defined by the function of the controller is generated. The pressure at the controller outlet is set by the control device as a function of the positive acceleration experienced by the pilot and consequently by the control device worn by him. The pressure at the controller outlet is increased linearly with increasing positive acceleration as soon as the acceleration exceeds a threshold value of 1.8 g.
The prior-art control device operates with a pneumatic control branch, in which mass elements are provided, whose inertia is utilized to detect positive accelerations, wherein the mass elements are displaced against the force of a spring in order to thereby bring about pressure changes, which are ultimately transmitted to a control chamber of a main valve, as a result of which a pressure setting dependent on the displacement of the mass elements is achieved at the controller outlet. The transfer function of the control device, i.e., the pressure at the controller outlet as a function of the positive acceleration, is ultimately determined by the coordination of the spring constants, the mass of the mass elements, the dimensioning of throttle openings and pipe sections in the pneumatic controller.
The progressive development of modern jet aircraft, especially of military jets, has made it possible to fly flight profiles with computer controls, which range from negative accelerations to positive accelerations and rapid transitions from negative accelerations to high positive accelerations. However, it has been found that physiological problems arise for the pilots during a rapid change from negative to positive accelerations. This is explained especially by the fact that blood vessels in the upper part of the body, especially in the head, which are dilated at negative accelerations, very rapidly drain large amounts of blood into the lower part of the body at the time of a rapid transition to positive accelerations, so that there is a risk of a so-called "red out," i.e., the blood flows too rapidly from the brain of the pilot and the brain is no longer supplied with a sufficient amount of blood as a result, as a consequence of which the pilot becomes unconscious.